Rotary switch with removable units



July 1, 195s M. A. TABET 2,841,660

` ROTARY SWITCH WITH REMOVABLE UNITS Filed April ll, 1956 2 Sheets-Sheer? 1 j ATTORNEY July 1, 1958 Filed April 1l, 1956 M. A. TABET ROTARY SWITCH WITH REMOVABLE UNITS 2 Sheets-Sheer" 2 INVENTOR ATTORNEY Michael A.. Tahet, Norfolln factuiingtoinpnny, Ene., ot Virginia Va., assigner to Tahet Manu- Norollr, Va., corporation The present invention relates to an electrical switch assembly wherein a swingable arm is adapted to individually engage cach contact of a group arranged in circular outline and circumferentially spaced from each other and the invention pertains to the construction and mounting of insulating plate or wafer carrying such contacts so that it may be removed from the association with the other parts of the switch assembly and from circuit mal-:ing engagement with terminals for the switch.

rThe prior art includes rotary type switches wherein a large number of conta-ets are arranged in circular outline and carried by an insulating wafer with a rotary arm adapted to engage each of the contacts as a shaft is rotated. Such switch structures often include a plurality of wafers assembled in stacked or juxtaposed relationship and the rotary arms of all of the wafers are rotated in unison. Such switch structures have the disadvantage that when there is a mechanical or electrical failure in any one of the assembled wafers the entire switch must be dismantled in order to remove and replace the defective unit. It is accordingly an object of the present invention to provide a switch structure wherein each wafer unit may be removed from association with the switch assembly and from the circuit making engagement with terminals of the switch so that any one of the wafers and the contact making elements thereon may be readily replaced.

Another object of the invention is to provide a plurality of adjacent wafer or panel type of switch units which may be operated by a shaft common to all of the units with the panels carrying contacts for the switch being n'iounted for sliding movement with respect to the supporting structure of the switch and the terminal contacts therefor so that any of the panel units of the switch assembly may be readily withdrawn and another unit slipped into a position so as to be operated by the shaft.

A more specific object of the invention is to provide a switch structure which includes a plurality of panels or plates mounted in face-to-face relation each having a group of contacts thereon arranged in circular outline with each group adapted to be engaged by a swingable arm mounted for rotation on each panel so as to engage any one contact of one group and to provide a slot in the panel and in the rotary structure so that any panel may be withdrawn from engagement with its terminal contacts and from an operative position in relation to the operating shaft.

@ther objects and features of the invention will be appreciated by those skilled in the art to which the invention pertains as the present disclosure proceeds and upon consideration of the following detailed description taken in connection with the accompanying drawings wherein several exemplary embodiments of the invention are disclosed.

in the drawings:

Fig. 1 is a perspective view of a switch assembly exhibiting the invention showing one of the plates in a .removed position.

fwi ce Fig. 2 is a perspective View of one of the plates in a position turned one hundred and eighty degrees from the position shown in Fig. 1 and with the rotor removed.

Fig. 3 is a sectional view ofthe rotor for one of the plates taken on the line .,-3 of Fig. 1.

Fig. 4 is a sectional view removed and taken on the line 5 4 of Fig. 2.

Fig. 5 is a sectional view through the switch frame with the terminal structure removed and taken on the line 5 5 of Fig. 1.

Fig. 6 is a sectional elevation of a rotor taken on the line 6 6 of Fig. 3.

Fig. 7 is a transverse section of the frame taken on the line 7 7 of Fig. 1 and showing the terminal structure in elevation.

Fig. 8 is a sectional plan view with the plates in position and taken on the line 8-8 of Fig. l.

Fig. 9 is a front elevation of a modified plate and rotor therefor.

Fig. 1G is a diagrammatic view showing the circuits that may be made through the contacts and conductors carried by both faces of one plate.

The invention is directed to a switch assembly including a plurality of plates or wafers each of which carries a rotary blade and each wafer or plate is so mounted in a frame that it maybe removed from the frame or housing and from circuit making engagement with xed terminal contacts. The contacts on each wafer are arranged in a circular outline and adapted to be engaged by an arm or blade of the rotor. The plates may have a group of contacts on each face thereof and a second rotary arm or blade adapted to successively engage the contacts on the second face. The plates or wafers are supported in side-by-side relationship so that each may be removed and replaced and the rotary Contact making device carried by each plate are adapted to be rotatedv in unison. The assembly may if desired be so constructed that the wafers or plates may be Withdrawn only when the rotors are in the o position and the wafers may be so constructed that they may be inserted in the frame in one position or when the plate is rotated through one hundred and eighty degrees.

Referring to the drawings there is shown at 10 in Figs. l, 5 and 8 a frame which may be formed so as to provide for substantially encasing or housing other parts of the switch assembly. lf the switch is to be supported so that its actuating knob 11 is to rotate about a horizontal axis the frame 1t) may be provided with lateral horizontally extending ilanges 12 and 14. The frame includes a wall 16 having a plurality of longitudinally extending grooves 17 and 18 therein. These grooves are in parallel relationship and extend lengthwise of the wall 16. Another wall 19 is provided with grooves 21 and 22 (Fig. l) which are arranged in parallel relationship and extend lengthwise of the frame. If the switch is to be mounted so that the actuating knob 11 to turn about a. horizontal axis the grooves 17 and 21 are desirably in the same vertical plane and the grooves 18 and Z2 are likewise in a common vertical plane.

rl`he frame 10 is designed to support a plurality of plates or panels 26 which are formed of insulating material. One of such plates is shown in a removed position in Fig. 1 while another is arranged within the frame 10 and removably supported therein by having is longitudinal edges accommodated in the grooves 17 and 21. The plates 26 are desirably of rectangular shape having a straight longitudinal top edge 27 and a straight bottom edge 28 which is parallel to the top edge 27.

The frame structure includes side walls 23 and 24 which form support for the walls 16 and 19 and also provide support for bearings for a shaft 29 actuated by the lcnob 11. The side wall 2d may he spaced a greater of a plate with the rotor.

aeaneeo f3 9 distance from the side wall 23 than shown in 1Figs. 1 and 8 and the walls 16 and i9 extended accordingly and provided with additional grooves to accommodate any suitable number of plates for wafers'in a position so that they may be retrievedV as described below.

The'plates 26 are of identical construction and the electrical conductors thereon and the contacts carried by each plate including the rotary switch arm which makes selective engagement with each of the contacts are the same and a description of one will serve to disclose the character of all of the wafers or panels and the switch parts carried thereby including the conductors which extend from the contacts to make circuit engagement with terminal contacts. Each plate 26 is provided with a rather large circular opening 29 and in the embodiment illustrated in Figs. l to 8 a slot 3l. extends lengthwise of the plate from the centralopening 29 to the forward edge 32 of the plate. This slot is for the purpose of permitting the transverse shaft 2li having a generally flat cross section to escape from the plate when it is withdrawn from the position Within the frame it?.

The face 34 of each plate 26 is provided with a plurality of contacts 36, 37 and 3b. These contacts are arranged in circular outline about the central opening 29 and the contacts .are circumferentially spaced from each other. Each plate Z6 is preferably formed of plastic material having electrical insulating characteristics and also being relatively rigid. The contacts may be partially embedded in the face 34 of the plate and a conductor 39 extends from the contact 26 and terminates ilush with the edge 32 of the plate. This conductor may be embedded in the plastic material forming the plate 26 and suitably anchored. A conductor il extends from the contact 37 and terminates tlush with the edge 32. A conductor 42 extends from the contact 33 and terminates flush with the edge 32 of the plate 26.

The opposite face d4 of a plate 26 as shown in Fig. 2 is provided with a plurality of contacts 46, 47 and 43 arranged in circular outline and circumferentially spaced from each other. A conductor 49 extends from the contact 46 and terminates flush with the edge 32 of the plate. A conductor Sl extends from the contact 47 and terminates at the edge 32. A conductor 62 extends from the contact 33 and terminates llush with the edge 32. The contacts carried by the face ed are arranged in staggered relationship to the contacts carried by the face 34.

The face 44 of each plate Z6 carries a ring shaped conductor strip 54 which extends around the perimeter of the opening 29. The ends of the conductor 54 are Hush with the edges of the slot 3l as shown in Fig. 2. A conductor 56 extends from the ring 3'4- and a portion 57 extends parallel with the edge Z?) of the plate and the portion 57 terminates flush with the edge 32'of the plate or wafer. A similar ring-shaped conductive member S (Fig. 5) is arranged around the perimeter of the opening 29 and is carried by the face 3d of `the plate 26. A conductor 59 extends from the ring 58 and this conductor includes a portion 61 which extends parallel with the edge 27 of the plate Z6 and terminates iiush with the edge 32. The conductor 6i is in electrical circuit relationship with the ring-shaped electrically conductor 5d.

The plates 26 and the contacts carried on the opposite faces thereof as well as the conductors extending from the contacts including the ring-shaped conductors 54 and S8 and the conductors leadingltherefrom may be partially embedded in the plastic material forming the plates 26. These plates and thel electrical conductive members may be formed by printed circuit technique. The partial ernbedding of these conductive members is shown in Fig. 4.

vA rotor 66 is mounted for rotation on each plate 26. The rotor 66 includes two metal discs 67 and 68 having good electrical conductive characteristics and these discs have a diameter slightly greater than theV diameter of the opening Z9. The discs may be secured to each other in spaced relationship by providing an insulating disc 69 therebetween as shown in Fig. 3. The diameter of the disc 69 is such as to lit within the opening 29 as shown in Fig.V 5. After the discs 67 and 68 are applied to opposite faces of a plate 26 and to opposite faces of the insulating disc 69 they may be rigidly secured to each other in any suitable manner such as by means of rivets 7l. These rivets also provide electrical connection between the discs 67 and 63. The discs 67 and 68 are provided with slots 72 and 73 which are in radial alignment with a slot 74 formed in the disc 69. The slots 72, 73 and 76 are of the same width as the slot 3l in the plate 26. The slot structure in the rotor extends from the periphery of the discs 67 and 63 in a radial direction beyond the axis of the rotor assembly as shown in Fig. l so that the shaft 2t) may be accommodated at the axis of the rotor structure when each plate 26 is in therposition within the switch frame 1d (Fig. 5). In this position portions of the conductors carried by each face adjacent the edge 32 are in circuit engagement with terminal contacts for the switch. The peripheral portion 76 of the disc 68 is in circuit making contact with the ring-shaped contacts 54 carried by the tace d4 of the plate 26. The peripheral portion 77 of the disc 67 is in engagement with the ring-shaped conductive member 58 carried by the face 34 of the plate 26.

The disc 67 carries a radially disposed blade 7d which may be formed integral with the disc 67. The blade 78 swings during turning of the rotor to engage the contacts 36, 37 and 33. During rotating movements the outer peripheral portion '77 of the disc 67 remains in engagement with the ring-shaped conductor 58. Thus a circuit may be completed between the conductor 5% and any one of the conductors 39, il or 42 by turning the rotor which swings the blade 7 8. The disc 68 carries a radially disposed arm or blade 79 which is adapted to swing over the face 44 of the plate 26. The blade '79 is adapted to engage the contacts d6, a7 and 48. The outer peripheral portion 76 of the disc 63 remains in engagement with the ring-shaped conductor 54. ln view of the fact that the contacts on the face 34 of the plate 26 are circumferentially displaced from the contacts on the face d4 when the switch blade 7S is in engagement with the contact 38 the switch blade 79 is in an intermediate position between the contacts 46 and 47 as shown in Fig. l0. Further rotation of the rotor to swing the blade 73 in clockwise direction in Fig. l0 will cause the blade 79 to engage the contact 47 and the blade 78 will be in a position between the contacts 38 and 37. The blade 79 breaksV engagement with each contact before the contact blade 78 moves into engagement with one of its contacts.

When the rotor 66 is turned so that the swingable blade 73 is in the position shown in Fig. l the blade 7 9 will be in a corresponding radial position and the slot in the rotor 66 will be in radial alignment with the slot 3l. This represents the olf position when the blade 78 overlies the conductor S9 which serves to complete a circuit to the rotor structure. ln a similar manner the blade 79 will overlie the conductor 56. Any one of the plates with its rotor in the o position as shown in Fig. 5 may be withdrawn from the frame id. The shaft Ztl which is of substantially rectangular shape in cross section and which is provided for operating the rotor 66 of each of the plates is then in position so that any one of the plates and the elements carried thereon may be Withdrawn from the frame. During such sliding movement of a plate the shaft 20 is accommodated in the slot structure of the rotor 66 and in the slot 3l of the plate being withdrawn.

When the plates are in a position within the frame l) as is the case with one plate 26 shown in Fig. l end portions of the conductors carried by the opposite faces of the plates are in circuit making engagement with terminal contacts maintained in xed relationship with respect in the slot 3l the plate continues its movem aesinet to the frame llt). The conductor 39 is in frictional engagement with a terminal contact 91. The conductor 41 is in engagement with a terminal contact 92 and the conductor d2 is in frictional engagement with a terminal 93. The conductor 61 is in'engagement with a terminal contact 94. The conductor 49 carried by the opposite face of the plate 26 is in engagement with a terminal contact 96 while the conductor 51 is in engagement with a terminal contact 97. The conductor 52 is in engagement with a terminal Contact 98 and the conductor 57 is in engagement with a terminal contact 99.

The terminal contacts structure as shown to the right in Fig. 1 and in Fig. 7 may be constructed in any suitable manner. In the embodiment illustrated it includes insulating strips lill which are spaced from each other as shown in Figs. 7 and 8 sutliciently to permit the for-- ward edge portion of each plate 25 to extend therebetween. The leaf spring type of terminal contacts are carried by the insulating strips 101 which may be supported by angle brackets E02 carried by the frame. Any suitable structure may be employed for holding the terminal contact structure in fixed relation to the frame l so that the conductors carried by the faces of insulating plates 26 will make circuit establishing engagement therewith when the plates are in a position within the frame.

One of the advantageous features of the present invention is that it is impossible to insert any one of the plates 26 improperly in the frame The plate 2d shown at the left in Fig. l may be inserted in the frame in the oriented position shown by moving it to the right. The edge 27 of the plate then enters the groove 22 and the edge portion 28 enters the groove i3. The plate is guided by the grooves as it moves to the right and into the frame. When the knob il is in the oi position shown in Fig. l the shaft Ztl is so disposed that its major dimension is in the position shown in Fig. 5. Thus during movement of the plate 26 the shaft is accc "nodated the frame. The slot structure in the rotor str ci when it is disposed in alignment with the slot 3l accommodates the shaft E@ and the plate may occupy the cosition with the conductors thereof engaging the te contacts and with the shaft 2@ disposed along the of the rotor do. The end portion of the conductor al will then engage the terminal Contact which may be utilized as one side of a circuit or circuits to be controlled. The plate 26 may be inverted from the position shown at the left in Fig. l and with the plate in the orien" shown in Fig. 2 it may be inserted in the frame the rotor structure 66 is in the position with its sic ture aligned with the slot 3l. The cdgc of th p 26 then enters the `groove 22 and the edge ent the groove t8. Under such circumstances the conductor if! will engage the terminal contact and the same side of a circuit or circuits to be controlled will agi-in se connected to the rotor structure 66. Electrical connection is maintained between the discs 67 and d of the rotor through the conductive rivets 7l or the like. Accordingly it is impossible to insert any one of the plates 2115 in an incorrect manner in the switch assembly.

The knob li is secured to the shaft 23 and serves to rotate the shaft and thereby actuate all of the rotors 66 carried by the respective plates. The knob ll may be provided with an index lit so that it may be readily aligned with the oposition shown in Fig. l.

It is not necessary to provide each or" the 'plates Z6 with a slot 31. A modified plate 26a is shown in Fig. 9 where the rotor 66a is devoid or a radial slot. in this embodiment the rotor 66a is provided with an opening 1.,., therethrough at the axis thereof which is of elongated rectangular shape in cross sectional area for accommodating the shaft Ztl. In this embodiment the shaft Ztl and its bearing 106 (Fig. 8) is so constructed that the shaft Zt) l position when may be withdrawn from the bearing ldd and through the side wall 23. rthus any one of the plates 26a may be removed from the frame and from circuit making engagement with the terminal contacts of the switch assembly. The shaft il@ is desirably withdrawn when the rotors dan are in an oft position as shown in Fig. 9 when the index ldd on the knob l1 will be radially opposite the Gif position.

-While the invention has been shown and described in connection with speciiic structural characteristics of a fr and particular type of terminal structure and one outline ci conductors on the face of the insulating plates it will be appreciated that changes may be made in all of these elements as well as the overall assembly. Modiiications in the details as well as the general organization f' Yde without departing from the spirit and scope .fenion as set forth in the appended claims.

what l claim and desire to secure by Letters Patent is:

l. .du electrical switch assembly comprising, plates of insulating material arranged in face-toface spaced relationship, a group of contacts arranged in circular outline on cach plate with the contacts of each group circumferentially spaced from each other, a blade mounted for rotation on each plate, said blades bein.a adapted to successively engage the contacts of one group during rotation thereof, conductors carried by each plate extending irom the respective Contacts thereon, means supporting said plates for guided movements in the plane of each plate, terminal contacts mounted in xed relationship with respect to said supporting means engaging the conductors carried by each plate, means for actuating said blades in unison when the plates are in positions with the c reductors thereon engaging said terminal contacts, and cb plato having a slot for accommodating a portion of ne actuating means during movement of a plate from a position engaging its terminal contacts.

Z. An electrical switch assembly comprising a frame, a plate of insulating material mounted for movement on said frame, said plate having an opening therethrough and slot extending lengthwise of the plate from said opening to one edge thereof, a group of contacts arranged in circular outline on said plate and circumferentially spaced from each other around said opening, conductors carried by the plate with one conductor extending from each contact to said edge of the plate, terminal contacts mf inted in hxed relationship with respect to the frame d conductors, a rotor mounted for turning over-seuls in said opening including a blade for engaging contacts, said rotor having an opening adjacent the is thereof, a shaft supported for rotation on said frame extending through said opening for turning the rotor, and said rotor having a radially disposed slot therein extending from said opening to the periphery of the rotor adapted to be aligned with the slot in said plate.

3. An electrical switch assembly comprising a frame having grooves therein, a plate of insulating material mounted for sliding movement in said grooves, said plate having an opening therethrough and a slot extending lengthwise of the plate from said opening to one edge thereof, a group of contacts arranged in circular outline on a face of said plate and circumferentially spaced from each other around said opening, conductors carried by said face of the plate extending from said contacts to said -dge of the plate, terminal contacts mounted in fixed relationship with respect to the frame in alignment with said grooves for engagement by end portions of said conductors, a rotor mounted for rotating movement in said opening including a blade for engaging said contacts, said rotor hnv'ng an opening at the axis thereof, said rotor having a radially disposed slot therein in communication with said opening adapted to be aligned with the slot in said pla.. a shaft mounted for rotation on said frame and extending through said opening in the rotor when the plate is in a position with end portions of the conductors engaging said terminal contacts.

asa-1,660'

4. An electrical switch assembly comprising, a frame, a plate of insulating material mounted for movement on said frame, said plate having a slot therethrough extending from one edge of the plate, conductors on said plate terminating at said edge of the p mounted in lixed relationship wL engaging end portions of said co' ber mounted for movement on said plate any two of said conductors, means ca for actuating said switch member, and t. modating a portion of said means during i, the plate away from said terminal contacts.

5. An electrical switch assembly comprisin a frame, plate of insulating mat rial mounted for guided movements on said frame in the plane of said plate, s; having a slot therethrough extending from one e carried by said plate terminating said edge plate, terminal contacts mounted in xed rela with respect to the trarne engaging end porticiM conductors, switch means mounted on said int portion of the plate tor bridging any two ol said conductors, a shaft carried by said frame ecgaginq and adapted to actuate said switch means when the plate is in a position with the end portions ci said conductors engaging said terminal contacts, and said slot accontmodating said shaft during movement of thc plate away from said terminal contacts.

6. An electrical switch assembly a plurality ot plates of insulating ma '.,l arranged face-tc--tace spaced relationship and mouned cn said frame for movement with re peet thereto with each plate movable inthe pla Ae thereof, eac plate having a slot therethrough ext nding from an edge of the plate to an intermediate portion thereof, conductors carried by each plate terminating at said edge o the L late, rminal cotact mounted in fixed relationsL J with l frame engaging end portions ot the conc by the respective plates, switch means mou terinediate portion ot each plate for lising, a traine,

t e engaging and adapted to actuate all of said switch s when the plates are in positions wn the portions oi the conductors thereon engaging said teli and said slot accommodating said shaft during m of any one or all of the plates away from the te" contacts.

7. An electrical switch assembly comprising, a frame, a plate of insulating materia1 nounled for o' said trame, said plate hating an ^pen and a slot extending from said o the plate, circuit making l for rotation on said plate withn doctors extending tnerefrom ai terminating at said edge or mounted in xed relationship with engaging said conductors,

and breaking means when the plate is in resina said conductors engaging said tern and s slot accommodating said shaft di plate from a position engag ng 8. An electrical switch assembly com Mising, having a lirstwall and a second wall, said rst wall having a plu therein, said second wall havi grooves therein aligned respecti the first wall, a plurality or" plates oi insu one edge orF each plate guided slidably 't the lirst wall and a second edge of each plage sl d an aligned groove in the second wall, plat.J t an opening therethrough, conductors on each plate tending to a forward edge thereof, a plurality of groups of terminal contacts carried by said trarne adjacent the forward edges of said plates with each group engaging 8 end portions ot the conductors carried by one plate, a rotor mounted within the opening in each plate for rotation with respect to the associated plateswitch blade means carried by each rotor for engaging the conductors on the associated plate, and means for actuating all of said switch blade means including a shaft detachably en-V ze, contacts carried by said terminal structure troni each other along both sides of said space, a

'd grooves with an end directed towards said terminal fruw-tre Vand supported for sliding movement into said spaced conductors carried by both faces of said late extending to said end of the plate and adapted to -esvectively engage said contacts when said end of the plate enters said space, rotary switch means carried by the plate for bridging any two of said conductors, and actuating means for said switch means includingra shalt in detachable engagement therewith.

l0. An electrical switch assembly comprising, a frame including two parallel walls, a terminal structure having an elongated space therein extending substantially at right angles to said walls, each wall having a groove therein confronting the other wall with said grooves alignedwith said space, contacts carried'by terminal structure spaced from each other along said space, a plate of insulating material having edge portions within said groovesV with an end directed towards said terminal structure and supported for sliding movement into said space, spaced conductors carried 'by a face of said plate extending to said end of the plate and adapted to respectively engage said contacts when the plate is pushed into said space, switchV means carried by the plate for bridging any two of said conductors, and actuating means for said switch means in detachable engagement therewith.

lli An electrical switch assembly according to claim l, wherein the conductors on one face of the plate at the ends thereof are staggered with respect to the ends ol' the conductors on the other face of the plate.

l2. An electrical switch assembly comprising, a frame including a hrst wall and a second wall parallel to the VFirst wall, a tirst terminal structure having an elongated space therein extending substantially at right angles to said walls, each wall having a groove therein confronting the other wall said set grooves aligned with said space, a second terminal structure arranged laterally of the rst terminal structure and having an elongated space therein extending substantially at right angles to said walls, each wall having another groove therein confronting the other wall with the second set of grooves aligned'with the space of said second terminal structure, contacts carried by each terminal structure, a plate of insulating material having edge portions within the first set of grooves with an end directed towards the lirst terminal structure,V

a second plate of insulating material having edge portions within the second set of grooves with an end directed towards the second terminal structure, said plates being slidable in said grooves with the ends movable into the respective spaces, conductors carried by a face ofV each plate adapted to engage the contacts or" the associated terminal structure, rotary switch means carried by each plate for bridging any two of the conductors thereon, and actuating means for said switch means including te of insulating material having edge portions within carried by a face of said plate terminating at one edge of the plate, terminal contacts mounted in fixed relationship with respect to said frame and in a plane dened by said plate engaging end portions of said conductors, switch means mounted for rotation on said plate for making and breaking circuits to said conductors, a knob mounted for rotation 011 said frame, and a shaft connected to the knob detachably engaging said switch means whereby the plate may be retracted while guided by said grooves to disconnect said conductors from said terminal contacts and withdrawn from said frame.

14. An electrical switch assembly comprising, a trame having grooves therein, a plate of insulating material mounted for sliding movements in said grooves, said plate having an opening therethrough, a group of contacts arranged in circular outline on a face of said plate and circumferentially spaced from each other about said opening, conductors carried by said face of the plate extending from said contacts terminating at one edge of the plate, terminal contacts mounted in fixed relationship with respect to said frame and in a plane defined by said grooves engaging end portions of said conductors, a rotor mounted within said opening for rotating movements, a blade on said rotor for engaging said contacts, a knob mounted for rotation on said frame, and a shaft connected to the knob detachably engaging said rotor whereby the plate may be retracted while guided by said grooves to disconnect said conductors from said terminal contacts and withdrawn from said frame.

15. An electrical switch assembly comprising, a frame, a plurality of plates of insulating material arranged in face-to-face spaced relationship and mounted on said trame for sliding movement with respect thereto with each plate movable in the plane thereof, conductors carried by each plate extending to one edge thereof, terminal contacts mounted in fixed relationship with respect to the frame engaging end portions of the conductors carried by the respective plate, rotary switch means mounted on each plate for bridging any two of the conductors thereon, a shaft detachably mounted on the frame for rotation with respect thereto extending through and engaging all of said switch means when the plates are in position with end portions of the conductors thereof engaging said terminal contacts, and said shaft being detachable so that any one or all of the plates may be withdrawn from the frame and from association with its terminal contacts.

16. An electrical switch assembly according to claim 2, wherein the contacts are so arranged that the blade does not engage any Contact when the slot in the rotor is aligned with the slot in the plate.

References Cited in the tile of this patent UNITED STATES PATENTS 2,616,994 Luhn Nov. 4, 1952 2,634,310 Eisler Apr. 7, 1953 2,644,063 Zikmund et al June 30, 1953 2,649,513 Luhn Aug. 18, 1953 

